This week you will have read that coffee prevents depression. I don't want to talk about this specific study – that would be too easy – but suffice to say, it was a sound piece of observational work, ludicrously over-interpreted in some quarters, and subject to the usual caveats. People who drink lots of coffee might be different to people who drink no coffee in all kinds of interesting ways, and any apparent relationship between drinking coffee and having a lower risk of depression could be down to these other factors. Maybe anxious people avoid coffee and have more depression. Who knows?

Now, traditionally, discussions about research for questions such as this will run: yes, it would be nice to have a large, randomised controlled trial on coffee preventing depression, because that would exclude these alternative explanations; but it's never going to happen, so let's just work with that we have.

I think that might be misguided. It's all very well to demand that medics, quacks, and politicians should do more and better trials. But actually, if there are questions about the efficacy of interventions that interest you, in your own life, then you could run a trial yourself, from your own home. Let me explain why this is a non-mad idea.

Firstly, recruitment shouldn't be a problem. From the extensive media coverage it gets, we can see that the health effects of coffee, for example, are interesting to the general population. In the past 10 days we've had coffee and depression, and coffee and stroke (and the Kill Or Cure website – an alphabetical list of all inanimate objects ever associated with cancer by the Daily Mail — contains many more entries on coffee). So people are interested in this question.

Secondly, it's practical. Trials are not hard to run online – never meeting your participants – if the intervention can be delivered remotely, and the resultscollected the same way. There are various randomised trials already being run that way, examining questions like which of two health-promotion strategies is best for reducing excessive drinking.

The only infrastructure needed is a simple online platform: one that can publish a research plan, accept registration from participants, randomly assign them into two groups, send each group their directions, and then collect structured follow-up data, before finally performing one simple statistical test on those results. This is just a few days' work, for a bored coder in a recession.

The main methodological problem with a coffee and depression trial is size. If our main outcome is depression, in people who are fine to start with, then that's quite an infrequent diagnosis. If your outcome is infrequent, then you need many more participants to detect a modest change in outcome between two groups. So ideally, our first pilot project would be something where the "event rate" is higher, to detect a change with a manageable group. If you drink a large amount of alcohol – I wish you wouldn't, but many will this evening – then you're very likely to get a hangover. Some people drink two pints of water before they go to bed. Does that work? Nobody knows. If we ran a trial online, we'd have the answer by tomorrow afternoon.

In fact, there are endless uncertainties in life, of real public interest, where trials might struggle to get past an ethics committee, or a funding body. Does squeezing spots make them disappear faster? Does bed rest really help clear a cold?

Yes, folk trials would have flaws. They would be "open label", which is to say, the participants would mostly know what intervention they were getting, of course. But for practical reasons, that's often the way in proper trials anyway.

A chaotically conducted, randomised folk trial would be, at the very least, a first stab at answering all these questions, with cautious interpretation.

Most online big-data projects mine information that already exists for patterns. A simple open-trials platform would let anyone who wants to propose, design, recruit and run a randomised trial online. Tell me what's wrong with this idea, but dismiss it outright and you deserve spots, a cold and a hangover.